1 Field of the Invention
The present invention relates to a developing device for copying machines, printers and the like.
2. Description of the Related Art
Conventional developing devices provide a toner carrying member, a regulating member that makes pressure contact with said toner carrying member, and a toner supplying roller that makes contact with said toner carrying member. In the aforesaid developing device, toner is supplied to the surface of the toner carrying member by the toner supplying roller so as to form a toner layer thereon, such that said toner is supplied to the surface of a photoconductive member by means of the rotation of the aforesaid toner carrying member, thereby performing the developing process.
Because the aforesaid developing device is constructed in such a way that the toner supplying roller and the toner carrying member make contact, and after developing, the residual toner layer remaining on the surface of the toner carrying member is disturbed, and the toner layer on the toner carrying member becomes nonuniform due to the transporting of toner to the aforesaid disturbed toner layer. Further, the toner receives an unnecessary electrical charge through the static electricity generated by the aforesaid contact, resulting in the disadvantage of producing fogging and variable density irregularities in the developed image.
A developing device having a toner supplying roller confronting a toner carrying member so as to maintain a space therebetween to eliminate the aforesaid disadvantages has been proposed in Japanese Laid-Open Patent Application No. 63-48576. In the aforesaid developing device, there is no touching contact between the toner supplying roller and the toner carrying member because the toner supplying roller and toner carrying member are maintained with a space therebetween, such that the residual toner layer formed on the surface of the toner carrying member is not disturbed. In addition, there is no unnecessary electrical charging of the toner, and post-development image characteristics can be stabilized.
On the other hand, an adequate quantity of toner is not maintained on the surface of the toner carrying member because a means for positively thrusting toner onto the toner carrying member is not provided in the previously described developing device. Accordingly, the quantity of toner supplied for developing is not enough, and the image density is reduced for images having a large surface area, thereby producing the disadvantages of missing dots (white spots), variable density irregularities, and reduced image quality.